1. Field of the Invention
The present invention relates to an optical communication element. More particularly, the present invention relates to an optical module for housing a plurality of active elements, such as a laser diode and a photo diode.
2. Description of the Related Art
In general, an optical module includes an electric circuit device, such as a printed circuit board, on which a laser diode, a photo diode, etc., are mounted. The optical module outputs an electric signal by converting a radio frequency signal into an optical signal or vice versa. As the information industry has progressed rapidly, a great amount of information is transmitted/received through an optical network at a high transmission rate. Accordingly, it is necessary to provide an optical module capable of transmitting/receiving mass data at a high transmission rate.
FIG. 1 illustrates a conventional optical module 10 for a multi-wavelength which includes a laser diode 11 and at least one pair of photo diodes 12.
In operation, the laser diode 11 receives an RF signal and outputs an optical signal by converting the RF signal into the optical signal. The photo diodes 12 receive the optical signal and covert the optical signal into the RF signal. The optical signal outputted from the laser diode 11 and the optical signal received in the photo diodes 12 have the same optical path. Thus, the optical path of the optical signals to be received in the photo diodes 12 must be shifted in such a manner that the optical signals having wavelengths corresponding to the characteristics of the photo diodes 12 can be received in the photo diodes 12. The optical module 10 transmits the optical signals along an optical axis of the laser diode 11 and is equipped with the thin film filters 14 and 15 corresponding to the number of the photo diodes 12. After the optical path of the optical signals has been shifted by means of the thin film filters 14 and 15, the optical signals are incident into the photo diodes 12 by passing through predetermined lenses 16 and 17. The lenses 16 and 17 are aligned in the optical path of the optical signals between the thin film filters 14 and 15 and the photo diodes 12.
FIG. 2 is a sectional view of another conventional optical module 100 for a multi-wavelength. As shown, the conventional optical module 100 includes a module body 101 in which a thin film filter 111 and a lens 113 are installed. A laser diode 102 is installed at one end of the module body 101 and photo diodes 103 and 104 are mounted at both side ends of the module body 101. In addition, an optical fiber 115 is coupled with the other end of the module body 101.
The optical module 100 having the above structure is integrally formed through an electric discharge machining process in order to form a mounting position of the thin film filter 111. However, since the structure of the conventional optical module 100 is complicated, it is difficult to fabricate the optical module 100 in mass production.
FIG. 3 shows yet another conventional optical module 200. As shown, the optical module 200 includes a module body 210 in which a laser diode 202, photo diodes 203 and 204, and an optical fiber 215 are installed therein. Further, thin film filters 211 are inserted into the module body 201.
However, the optical module 200 having the above structure uses a plurality of components, thus increasing the manufacturing cost. In addition, since the thin film filters 211 are inserted into the module body 201, a tolerance between parts of the optical module 200 must be considered, so that precision of the optical module 200 may be degraded.